It is shown that the fundamental expression for the complex permittivity epsilon(s)* of a dilute suspension of monodispersed, spherical particles, epsilon(s)* = epsilon(e)*(1 + 3 phi d*), where epsilon(e)* is the complex permittivity of the suspending medium and d* the dipolar coefficient, is strictly valid for any value of the volume fraction phi of particles in the suspension, provided that d* is interpreted as the ensemble average value of the dipolar coefficient of the particles and is defined in terms of the macroscopic electric field in the suspension. (C) 2006 Elsevier Inc. All rights reserved.